Question: The sum of $2$ consecutive integers is $139$. What is the first number in this sequence?
Explanation: Call the first number in the sequence $x$ The next integer in the sequence is $x + 1$ The sum of the $2$ consecutive integers is: $x+ (x + 1) = 139$ $2x + 1= 139$ $2x = 138$ $x = 69$ Thus, the first number is $69$.